In this series of tutorials, we'll be taking a detailed look at each of mental ray's lens nodes. Each video is a self-contained tutorial centering on one of mental ray's nodes. This means that these tutorials can be viewed in any order you wish, allowing you to jump straight to the content that is most relevant to you. Over the course of these tutorials, we'll learn how each node works and the best practices to utilize for attaining desired results while saving time. Software required: Maya 2008 and up.
Kyle was one of the first authors for Digital-Tutors (now a Pluralsight company) and has been a part of the team for over 10 years. Kyle began his career in computer graphics education as a college instructor and worked as a Digital-Tutors rendering tutor and curriculum manager since 2002.
Introduction and Project Overview [Autogenerated] in this lesson will explore the uses of the photographic exposure lens. Shader. So this is a Lynn shooter that allows us to achieve tone mapping effects very similar to the simple lens Shader. The only difference is that the photographic exposure is actually based on some of the controls of a real camera. So let's take a look at what we have. So right now we have in this starting seen just a very simple render, and this is right now using this simple exposure control. So let's take a look at how we can actually swap this out for the photographic exposure. So you may recall, if you've had a chance to go through our lesson on using the physical sky, that whenever we add that in that there is automatically connected for us a photographic or rather, a simple exposure. So let's disconnect. This will just simply break the connection. And now let's plug in a photographic exposure. So let's scroll down. And here's our exposure Photographic. All right, so what this plugged in? Now you can see if you are familiar with some of the settings of a traditional camera that we do have a lot of these options available to us. Things like the film sensitivity, the camera shutter speed and the F stop before we can actually rented this out. There is a couple of changes that we need to make here in the scene. One is to go back to the physical sky and actually adjust the RGB unit conversion. If we were to simply render this scene out right now, this would pretty much come out black. And that's because the photographic exposure has a different sensitivity level than the simple exposure. So, in order to base this physical sky on real world luminous values, what we want to do is make sure that we are GNB units are all set to a value of 0.318 and now we can actually again Matt. This based on riel loom in its values, and now this gives us the control of the camera that would be much closer to the film settings that we would use in real life. So let's just start with the settings right now set to default. So let's save this for comparison and rear ender, can you notice that once the render completes that overall this is still quite a bit darker than what we had before. So let's start to make some adjustments to these. We can start by doing something like in greasing the film's light sensitivity so you can take the ice so up from about 100 up to something like 300 we'll start with that so you can start to see how that can help us to brighten up the image. Now we have something that's quite a bit closer to what we had before. We can also start to increase things like the camera shutter speed. So with this particular value, the higher the shutter speed, the faster the shutter closes, which means less light comes in. So this is a value that as we start to increase it, we should actually start to darken the image again because we're increasing the speed of the shutter and you can see again. That's exactly what we get. Now we're back to having something that's a little bit darker than what we had before, so we can either start to decrease our shutter speed or we can start to lower our F stop or R F numbering in this particular situation, is what the attributes called. So again, this is another situation where higher values will typically produce darker results because you're actually making the aperture smaller as this goes higher and higher so we can start to maybe drop this down to an F stop of eight. That should start to brighten up our image fairly significantly and again. You can see that's exactly what we get. So, really, this level of control that we have does become fairly easy to manage because these are very closely related to the types of attributes in the types of settings that we would use on a real camera. So you can see, as I'm slowly starting to increase my number of F stops that weaken start to kind of dark in this image, back up and start to eliminate a little bit of this washed out effect that we had before. So we also have the controls for the actual color results that finally get displayed back to us in addition to these overall exposure controls. So the first that we have is the vignette ing, which is the tendency for more light to be focused in the center of the image toward the center part of the film as opposed to the outside. So with a higher amount of vignette ng, we should start to see more of a darker kind of a halo around the outer parts of our image again just to simulate the effect that we would get with a real film. So let's start to increase this a little bit and rear ender, and again you can see that's exactly what we get. We now have a little bit more of a darker kind of area out here and Maur the light is concentrated toward the center part of this image again, just simulating a little bit more closely the look of some kind of a film photograph. So we also have the burn highlights and the crush ______. So this is the ability now to start to overexpose parts of our image with the burn highlights. Right now, with this at 20 we really don't have any kind of a burn in effect that starts to happen so we can start to increase this and as this starts to go higher and higher, we can start to get more and more of a burn effect on our highlights. So we'll see this for comparison. And let's start to see what we can get, all right. And once that's done rendering, you can see that now we, compared to what we had before, are now starting to get a little bit more of a burning and a little bit more of an overexposed effect in some of these brightest areas of our image. All right, and similarly, we could do the same thing with the crush ______. So as this starts to increase a little higher, this should now start to crush out and start to darken some of the darkest parts of our image even further. And you can see with that that we now start to darken up and start to really increase the overall darkness of some of these darkest areas of the image. So, really, we do have the ability with these controls to kind of increased the amount of contrast really between these darkest areas and these lightest areas as a way of either increasing the overall look of our image is starting to get something more realistic, or we can really kind of push these values and start to get something that's much more abstract and a little bit more artistic. All right, so that's a look at how we can simulate some Rhea World film type looks with the use of this exposure. Photographic lens shader.